I have been seeing some commercials lately for cars with collision avoidance systems that warn drivers when they are approaching an obstacle too fast and will last minute brake if your about to hit something. Anybody have any idea how this system works? Is it judging distances via radar or laser? The commercial showed an example of a car driving the highway in the fog and the system could see a slow moving car on the highway through the fog. So I am doubting this is laser... Thoughts?